1. Field of the Invention
The present invention is generally directed to a seal for maintaining a fluid tight junction between a pair of ducts or pipes and particularly concerns a seal ring for sealing between an aircraft jet engine and its exhaust duct and nozzle.
2. Description of Prior Developments
Numerous types of seal rings have been designed for sealing against fluid leakage through the junction formed between a pair of axially connected ducts or pipes. Notwithstanding the large number of seal designs currently available, a need currently exists for a seal ring which meets the particular requirements for sealing between an aircraft jet engine and a jet engine exhaust duct which is mounted to and supported by the aircraft airframe. Prior production jet engine aircraft designs which rigidly mounted a jet engine to its exhaust duct and nozzle did not require the seal provided between the jet engine and exhaust duct to accommodate as many variables or fulfil as many functions as those associated with modern aircraft designs having airframe-mounted, isostatically-supported exhaust ducts.
More particularly, a seal ring which seals the unction between a jet engine casing and an associated airframe-supported exhaust duct and nozzle must allow the exhaust duct and nozzle to move relative to the jet engine casing, yet facilitate engine installation and removal while minimizing the leakage of exhaust gasses during engine operation. Specifically, such a seal ring must accommodate relative axial motion across the sealed junction between the engine casing and exhaust duct as well as accommodate angular misalignments between the longitudinal axes of the engine casing and exhaust duct. This seal ring must further accommodate radial misalignment or eccentricity between these sections of the jet engine and must compensate for changes in diameter between these sections due to thermal expansion and contraction and pressure loading.